You don't need a chemistry degree to figure out what skin-care products are right for you.

"Between all the ads that claim the latest skin-care miracles, and the hundreds of products at the mall skin-care counter, people really need some guidance about what they need and what actually works," says Angie Wick, aesthetician at UW Health Transformations.

Wick says research has shown that there are three substances that can actually protect against, or repair, signs of aging.

Retin A (Vitamin A) or Retinol (Vitamin A Derivative)

"Skin-cell turnover is an important process in skin care," says Wick. "Vitamin A is a tried and true ingredient that exfoliates the skin."

Wick recommends using a pea-sized amount because putting more than that on skin can cause redness and peeling.

Topical Vitamin C

Wick says vitamin C is an antioxidant that stimulates collagen production and minimizes fine lines and wrinkles when applied topically.

"Vitamin C can be unstable and lose its effectiveness quickly," says Wick. She says to look for the stable form of vitamin C, L-ascorbic acid.

Growth Factor

Growth factor, a naturally occurring substance, can increase collagen production. It maintains the structure of connective tissue and plays a role in wound healing. Wick says there are very few commercially available skin-care products with growth factor, but there are products in development.

What claim is really bogus? Wick says products touting collagen--a structural protein in the skin--to be applied topically are completely ineffective, for the simple reason that the collagen molecule is too large to penetrate human skin.

Typically, skin-care products sold at medical practices have more potent and effective ingredients compared to those sold in department stores. Wick says the stronger products have slightly higher prices but the costs are competitive with what's sold in department stores.